Flat screen.



S. M. MYRTIN.

FLAT SCREEN. `APPLIGA'IION FLBD 11.11124, 1910.

' Patented May 21, 1912.

LANOUILAPH co..wAsHlN'uroN D c unirse srkrris PATENT carica svEN 41vrEI`.cHEE MYRTIN, 0E STOCKHOLM, SWEDEN.

FLAT SCREEN.

Specification of Letters Patent.

Patented May 21, 1912.

Application filed August 24, 1910. Serial No. 578,751.

To all whom it may concern: y

Be it known that I, SvEN MELCHER MYR- y TIN, a subject of the King of Sweden, re-

siding at Stockholm, Sweden, have invented certain new and useful Improvements in Flat Screens, of which the 'following is a specification. Y Y

The fiat screens hitherto in use are so calledV suction screens, "infwhich the pulp, z'. e. cellulose ber pulped in water, is sucked through the screen plates by membranes which are set in an up and down motion.

Such screens possess, however, small ca` pacity for production, besides which the membrane is easily worn out and must be renewed.

The present invention, bywhich'these inconveniences are removed, relates to flatscreens built upon the principle of communieating vessels and in which the pulp moves from below upward and pulsation is effected in the pulp by means of a piston.V

The invention consists essentially ther-ein,

that the piston, arranged in the channel of the screen opposite the screen-plates, is reciprocated vertically by means of eccentrios on crank-arms, a play existing around such piston between the same and the wall of the channel. This arrangement of the piston has for its object to distribute the thrusts caused by the same in the pulp as uniformly as possible on the whole surface of the screen-plates in order to give a more4 effective hindrance to the stopping of the screen-plates. This arrangement can be combined with fixed' ribs arranged at the lower side of the screen-plates and set obliquely to the direction in which the pulp moves. y

In the accompanying drawing a flatscreen constructed according to the invent-ion here in question is shown.

Figure l shows the flat-screen looked at from the front, Fig, 2 a vertical cross-section and Fig. 3 the same in plan view.

A tank built ony the principle of communicating vessels has a larger chamber,

the inlet-chamber 1, and a smaller chamber, the outlet-chamber 2, which 4together form the communicating vessels and are separated from each other by a screen-plate wall 3. The bottom of the tank is softly rounded 0H, whereby the motion of the pulp against the screen-plate wall isl facilitated. Theslits o-rholes of the latter may be of any suitable shape, and if they are conical,

their smaller opening is in the opposite di-V rection of the motion of the pulp.

The pulp is conducted into the inlet chamber 1 through the upper open'end of it and carried off through an overfiow 11,

`which for that purpose is fixed at a properV yconnecting rods, a play existingar'ound the pistons between t-he same and the wall of the inlet chamber. When the shaft makes about 150 to 200 revolutions per minute the pistons in their downward motion cause shocks in rapid succession in the liquid. e Vhen the eccentrieity is about 15 to 20 mm.,

the lateral motion or stroke of the plates is slight. The eccentrics 6 are bestv fixed to the shaft 5 in such a way that for example two pistons go up, as the othervtwo go down. Through such an arrangement of the eccentrics a more uniform distribution of power on the shaft is also obtained, be- ,sides which the pistons willy also to a certain extent balance each other, whereby the consumption of power is reduced. As the movable parts only consist of eccentrics, the i' machine manifestly moves noiselessly. The separate eccentrics can, if want-ed, be provided, with arrangements for varying kthe eccentricity, so that the latitude of motion kof the pistons can be increased or decreased just as required. It is obvious that the flatscreen can be fitted with a smaller or larger number of pistons and eccentrics'than four.

As has been said, the .pistons are hanging free in the pulp withoutV tightly fittingthe walls. The space between the pistons and between the pistons and the walls is arranged in such a manner that the speed of the current and the pulsation of the pulp are in the most favorable proportion to each other. i

The pistons may however, as is shown in the drawing, be provided with valves 11, which open with the upward motion, whereby the consumptionof power is reduced,

The inlet-chamber may also be divided up into two or more sections by means of transverse walls 12, with one or more pistons operating in each section. Close to the wall 13 there is fitted a register 14, which hangs upon rods 15 and may be regulated by means of nuts 16. 17 are lists for guiding the said register. By means of the register the speed of the current of the pulp can be regulated. Fiber knots and other coarse objects can be drawn 0E now and then by means of a tube 18 fitted in the bottom or end of the apparatus. The apparatus is also provided with one or more cleaning shutters 19, whereby the cleansing of the apparatus takes place. As the screen-plate wall has the wider openings turned upward it is easy to wash them clean, and there is no need of raising it for that purpose.

When the coarser particles, as mentioned, are drawn off through tube 18 a portion of usable fiber follows of course also. To utilize this it is best to arrange in suoli a mank ner that the said coarser particles from one or several screens are conducted into a separate screen, of a smaller size than the former, and preferably in the lower part of the inlet chamber, wherefore in that case the flat-screen is fitted with an inlet-valve (not shown) for the pulp in the lower part of the inlet-chamber. Simultaneously pure water is introduced into the lower part of the inlet-chamber. The said particles will thus be subjected to a washing process and the useful fibers separated and passed through the screen-plate wall. In this manner an absolutely continuous operation with regard to both pulp and fouling can thus be carried on with a couple of screens.

In order to increase the effect of the apparatus a number of fixed ribs 20 or such like, is arranged at the lower side of the screen-plates and set obliquely to the direction in which the pulp moves. These operate therefore as a sort of sand catchers in such a manner that, when there is more foul matter in the pulp, this strikes the ribs and is stopped in its motion and sinks down. The ribs are, in contradistinction to certain other machines, in which fixed ribs are used, fitted close to the screen-plate wall, whereby the liquid close to the latter is kept cleaner. One or more rows of ribs may be used, and the ribs in one row may be arranged in zigzag against the ribs in an adjoining row.

I claim 1. In apparatus of the class described, in combination, a tank, said tank having an inlet chamberV and an outlet chamber within said inlet chamber and communicating therewith, a screen positioned between said chambers, said inlet chamber being provided with an upwardly extending portion, a shaft, eccentrics carried thereby and pistons supported by said eccentrics and positioned within said upwardly extending portion, whereby rotation of said shaft will reciprocate said pistons in the direction of the length of said portion, said pistons being spaced from one another and from the walls of the tank to provide for play.

2. In apparatus of the class described, in combination, a tank, said tank having an inlet chamber and an outlet chamber within said inlet chamber and communicating therewith, a screen positioned between said chambers, a plurality of obliquely set ribs xed adjacent the lower side of said screen, said inlet chamber being provided with an upwardly extending portion, a shaft, eccentrics carried thereby yand pistons 'supported by said eccentrics and positioned within said upwardly extending portion, whereby rotation of said shaft will reciprocate said pistons in the direction of the lengthpof said portion, said pistons being spaced from one another and from the walls of the tank to provide for play.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

SVEN MELCHER MYRTIN. Witnesses:

J. F. A. RUTBCK, Tons'rEN MELINDER.

Copies of this patient may be obtained for ve cents each, by addressing the Commissioner of Patents. Washington, D. C. 

